Rapid present development of unmanned aerial vehicles is rather unstructured. Starting from general
systems theory we formulate classification of unmanned aerial vehicles (UAVs) that properly groups diverse produced unmanned aerial
vehicles, along with their currently unproduced, yet possible types. First we structure the context of applications of UAVs using
systems thinking. Secondly, we divide UAVs according to their function in environment: transfer of mass, energy and information.
Thirdly, we further divide UAVs following with exchanges between them and environment which do not perform UAVs main predicted
function. Fourthly, we analyse possible types of UAVs and divide them based on the structure of their lift-creating element, on their
regulating programmes, and on the type of their power-plant.

We deduce guidelines for researchers and practitioners regarding prospective focuses in the field of unmanned aerial
vehicles.